- The park covers one acre with approximately 1,000 feet of saltwater shoreline on Spieden Channel. A maximum of 16 persons are allowed to camp overnight at the primitive water trail campsites on the island. There is one composting toilet. No drinking water is available on the island and garbage must be packed out.
Of special interest are the wildflowers that bloom from April through June.
This park is part of the marine parks and boat moorage system. Facility use is first come, first served, with continuous moorage limited to three consecutive nights. Fees are charged year around. Call (360) 753-5771 for a fee update as all fees are subject to change.
Camping and wildflower viewing are popular island activities.
Posey Island State Park is located one-fourth mile from the northwest end of San Juan Island in San Juan County. It is accessible only by boat.